Here is the piece I came up with:
This was too big to scan in one go; somewhere between a3 and a2 size, so in the process the top right looks a little blurry.
Drawn initially with pencil, then with a pot Winsor & Newton black indian ink and a brush, a kuretake waterbrush filled with an ink solution and a set of Faber Castell 'Shades of grey' pens.
Some work in progress:
Inks before wash: